In this first submission phase I proposal, the investigators propose to conduct the initial development of a device for performing hemoglobin measurements on pediatric patients. The major benefits of the proposed device are that it will be essentially painless, and that less than 1 microliter of blood is sampled. The proposed device will consist of a consumable sampling device that can be read in a hand held optical detector. The consumable sampling device will be made of an integrated silicon needle and curette with window. The components will be etched from silicon wafers using standard micro-fabrication techniques; the wafers are then bonded using high temperature fusion. When the blood is drawn through the needle into the curette, it will be hemolyzed by a detergent solution. The curette will then be inserted into the detector and the optical absorbance of oxy-hemoglobin, deoxy-hemoglobin, and methemoglobin will be measured using 3 light emitting diodes (LEDs). The concentrations of the 3 hemoglobin species will be determined by a microprocessor employing 3 simultaneous equations; the total hemoglobin concentration may then may calculated. There are 4 tasks proposed in Phase I. The first is to demonstrate a feasible hemoglobin assay based on the absorbance of light emitted from 3 LEDs with peak emission wavelengths at or near the absorbance peaks of the 3 hemoglobin species. The second is to design and fabricate experimental consumable sampling units. The third is to design and fabricate the test electro-optical instrumentation. The proposed instrument will use analog circuitry to manipulate the consumable unit to penetrate the skin and take a sample, retract it, to align the curette window with the optical system, to read the absorbance, and to calculate and display the resulting hemoglobin concentration. In the final task simultaneous measurements will be made on the test device and an unspecified commercial hemoglobin tester in order to determine the precision and accuracy of the test device. The investigators conclude that since the photometric method of hemoglobin concentration performs well with many different types of curettes, that a poor result from the test device would indicate problems specific to the micro-sampling technique. PROPOSED COMMERCIAL APPLICATION: The blood testing product that will emerge from this R & D program will be of particular benefit to pediatric patients because of its lack of pain and very small sample volume. Its ease of use will also make it attractive for home health care, nursing homes, and self- testing. In addition, rapid on-site measurement of methemoglobin will find application in occupation safety and health programs.